5.9L 24v Cummins ISB

5.9L Cummins ISB Specs & Info

In 1998, the 12v Cummins was phased out in favor of a redesigned 24 valve version of the engine, the 5.9L Cummins ISB (often referred to simply as the 24 valve Cummins). The ISB featured a Bosch VP44 rotary type injection pump until 2003, when the injection system was upgraded to a Bosch high pressure common rail. Power output and performance potential were significantly increased thanks to the common rail injection system. For the 2001 model year, an optional High Output (HO) version of the 24v Cummins was made available, which offered an increase in output - it was only available with a a manual transmission. The 5.9L Cummins was altogether retired mid-way through the 2007 model year, being replaced by the more emissions friendly 6.7L Cummins.

The acronym "ISB" stands for Interact System, B Series. It represents the fact that the engine uses an electronically controlled injection system, and is part of Cummins "B Series" engine family. All 24v Cummins were assembled at the company's Columbus, Indiana assembly plant, the same city in which the "Cummins Engine Company" was founded. For 2004, the engine was selected as one of Ward's "10 Best Engines" for the year. Production of the 5.9L ISB ended completely (all applications) in June of 2009.

High Output 24v Cummins

A high output (H.O. or HO) version of the 5.9L Cummins was available for the 2001 to 2004 model years. For 2001 and 2002, the HO Cummins boasted an additional 10 horsepower and 45 lb-ft of torque. In 2003, the HO model produced a whopping 70 horsepower and 95 lb-ft more than the standard turbodiesel. And for 2004, the optional high output engine claimed 20 horsepower and 45 lb-ft of torque greater than the standard model. The HO Cummins was not available in California, which has historically been a state with stricter emissions regulations than those imposed at the Federal level. The NV5600 6 speed manual transmission was the only transmission available mated to HO models of the Cummins, as at the time the available automatic was not rated with an adequate input capacity. High output models featured higher compression and a unique engine calibration to provide the additional performance.